Discrimination between poultry eggs on the basis of some observable quality is a well-known and long-used practice in the poultry industry. “Candling” is a common name for one such technique, a term which has its roots in the original practice of inspecting an egg using the light from a candle. As is known to those familiar with eggs, although egg shells appear opaque under most lighting conditions, they are in reality somewhat translucent, and when placed in front of direct light, the contents of the egg can be observed.
Eggs which are to be hatched to live poultry are typically candled during embryonic development to identify clear, rotted, and dead eggs (collectively referred to herein as “non-live eggs”). Non-live eggs (also referred to as non-viable eggs) are removed from incubation to increase available incubator space and also reduce the risk of bio-contamination. In many instances it is desirable to introduce a substance, via in ovo injection, into a live egg (also referred to as a viable egg) prior to hatch. Injections of various substances into avian eggs are employed in the commercial poultry industry to decrease post-hatch mortality rates or increase the growth rates of the hatched bird. Examples of substances that have been used for, or proposed for, in ovo injection include vaccines, antibiotics and vitamins.
In ovo injections of substances typically occur by piercing an egg shell to create a hole therethrough (e.g., using a punch or drill), extending an injection needle through the hole and into the interior of the egg (and in some cases into the avian embryo contained therein), and injecting one or more treatment substances through the needle. Such devices may position an egg and an injection needle in a fixed relationship to each other, and may be designed for the high-speed automated injection of a plurality of eggs. The selection of both the site and time of injection treatment can also impact the effectiveness of the injected substance, as well as the mortality rate of the injected eggs or treated embryos.
In commercial poultry production, only about 60% to 90% of commercial broiler eggs hatch. Eggs that do not hatch include eggs that were not fertilized, as well as fertilized eggs that have died. Infertile eggs may comprise from about 5% up to about 25% of all eggs in a set. Due to the number of non-live eggs encountered in commercial poultry production, the use of automated methods for in ovo injection, and the cost of treatment substances, an automated method for identifying live eggs and selectively injecting (or selectively contacting) only live eggs, is desirable.
An egg may be a “live” egg, meaning that it has a viable embryo. FIG. 1 illustrates a live poultry egg 1 at about day one of incubation. FIG. 2 illustrates the live egg 1 at about day eleven of incubation. The egg 1 has a somewhat narrow end in the vicinity represented at 10 as well as an oppositely disposed broadened or blunt end portion in the vicinity shown at 20. In FIG. 1, an embryo 2 is represented atop the yolk 3. The egg 1 contains an air cell 4 adjacent the broadened end 20. As illustrated in FIG. 2, the wings 5, legs 6, and beak 7 of a baby chick have developed.
An egg may be a “clear” or “infertile” egg, meaning that it does not have an embryo. More particularly, a “clear” egg is an infertile egg that has not rotted. An egg may be an “early dead” egg, meaning that it has an embryo which died at about one to five days old. An egg may be a “mid-dead” egg, meaning that it has an embryo which died at about five to fifteen days old. An egg may be a “late-dead” egg, meaning that it has an embryo which died at about fifteen to eighteen days old.
An egg may be a “rotted” egg, meaning that the egg includes a rotted infertile yolk (for example, as a result of a crack in the egg's shell) or, alternatively, a rotted, dead embryo. While an “early dead,” “mid-dead” or “late-dead egg” may be a rotted egg, those terms as used herein refer to such eggs which have not rotted. Clear, early-dead, mid-dead, late-dead, and rotted eggs may also be categorized as “non-live” eggs because they do not include a living embryo.
There are other applications where it is important to be able to distinguish between live (viable) and non-live (non-viable) eggs. One of these applications is the cultivation and harvesting of vaccines via live eggs (referred to as “vaccine production eggs”). For example, human flu vaccine production is accomplished by injecting seed virus into a chicken egg at about day eleven of embryonic development (Day-11 egg), allowing the virus to grow for about two days, euthanizing the embryo by cooling the egg, and then harvesting the agnostic fluid from the egg. Typically, eggs are candled before injection of a seed virus to remove non-live eggs. Vaccine production eggs may be candled one or more days prior to injection of a seed virus therein. Identification of live eggs in vaccine production is important because it is desirable to prevent seed vaccine from being wasted in non-live eggs and to reduce costs associated with transporting and disposing of non-live eggs.
Some previous candling apparatuses have employed opacity identification systems in which a plurality of light sources and corresponding light detectors are mounted in an array, and wherein eggs are passed on a flat between the light sources and the light detectors. Unfortunately, such conventional candling techniques may have somewhat limited accuracy due to different categories of eggs having similar optical densities (e.g., live and rotted) resulting in similar levels of transmitted light. Light opacity identification systems can operate at speeds equivalent to about 300,000 eggs per hour and successfully identify clear eggs from a stream of eggs. However, some eggs identified as being live may in fact be non-live (e.g., rotted eggs, mid and late dead eggs).
Other previous candling apparatuses have employed embryo heartbeat detection capable of detecting live and non-live eggs. However, these systems require the detection tooling to contact the eggs in order to create a mechanical light seal for detection purposes, which may present several problems. First, the throughput parameter is slowed down because the eggs must be stopped while the detection tooling head is lowered and raised in order for each detection tooling to contact a respective egg. Next, mechanical contact with the non-live eggs, particularly with the rotted eggs (which can explode when contacted), may undesirably introduce contamination into the detection system, which could potentially be transferred to subsequent live eggs during further processing. Finally, the emitter-detector configurations in previous heartbeat detection systems are difficult to position mechanically to allow for desired throughput, wherein incomplete sealing may result in light leakage interfering with the desired transmitted signal.
Accordingly, it would be desirable to provide a candling apparatus implementing a heartbeat detection system capable of accurately distinguishing live and non-live eggs without making contact therewith during operation and without the use of a mechanical light seal. Furthermore, it would be desirable to provide an associated method that would facilitate heartbeat detection of live eggs in a high throughput and accurate manner.